JP3935491B2 - Electron emitting device, electron source, image forming apparatus, and television - Google Patents

Description

The first of the present invention relates to a cold cathode electron-emitting device, and more particularly to a surface conduction electron-emitting device.
The second of the present invention relates to an electron source, an image forming apparatus, and a television provided with the surface conduction electron-emitting device.

  Conventionally, field emission type, metal / insulating layer / metal type, and surface conduction type are known as cold cathode electron-emitting devices.

Field emission type Among them, the field emission type with a sharp emitter shape has an emission efficiency of nearly 100% and is the most efficient, but requires complex film formation and pattern formation to process the emitter shape, There are also problems in processing accuracy and large area.

Surface Conduction Type On the other hand, the surface conduction type disclosed in Non-Patent Document 1 and the like has an advantage that it does not require high-level fine processing and can easily be increased in area. FIG. 9 is a top view showing a conventional surface conduction type element structure. FIG. 10 is a sectional view of the element.
Electrodes 21 and 22 such as SnO ₂ and Au are formed on a substrate 1 made of glass, ceramics, plastics or the like. Reference numeral 32 denotes a groove formed between the electrodes or an altered high resistance portion. The electrodes 21 and 22 can also be formed as separate electrodes by a method such as photolithography. As another method, the high resistance portion 32 is formed by a method called laser trimming or energization forming after forming the same electrode. The method is taken. In such a structure, when a voltage is applied to both ends of the electrode and a current is passed in parallel to the film surface, electrons are emitted from the high resistance portion by the tunnel effect.

The energization forming method does not require a high degree of microfabrication for electrode formation. However, electrons are likely to flow to the gate 22, so that electron emission efficiency is poor, current consumption increases, and the emitter 21 and the gate are easily destroyed. there were. In addition, the width of the high resistance portion obtained by this method is relatively wide, and there is a problem that a high voltage is required for electron emission.
Further, the energization forming method has a problem that the reproducibility of forming the high resistance portion is low, and it is difficult to obtain uniform emission characteristics when the emission elements are formed in an array. Moreover, since the work function of the electrode material to be used is high, there is a problem that the emission efficiency is low.

  On the other hand, when forming a pattern by photolithography or the like, there is a problem that it is difficult to uniformly control the distance between narrow electrodes. Moreover, since the work function of the electrode material to be used is high, there is a problem that the emission efficiency is low. In addition, in any method, there is a problem that the characteristics are easily changed by the adsorption of impurities onto the electrode.

Non-Patent Document 2 discloses a method in which ultrafine particle films of PdO are used for the electrodes 21 and 22 and a minute gap is formed between the electrodes by forming treatment. When a voltage is applied between the emitter and the gate, electrons are emitted from the gap by the tunnel effect. This method has a problem that although the emission voltage is low, the emission efficiency becomes extremely low. In addition, since the effect of the forming process depends on properties such as the film thickness of the ultrafine particle film, there is a problem that it is difficult to obtain uniform release characteristics. Moreover, since the work function of the electrode material to be used is high, there is a problem that the emission efficiency is low. In addition, there is a problem that characteristics are easily changed by adsorption of impurities on the electrode.
Patent Document 1 discloses a technique for stabilizing electron emission characteristics by depositing amorphous carbon or graphite by energizing a surface conduction type high resistance portion in a vacuum. In this case, however, the deposition of amorphous carbon and graphite depends on many factors such as the carbon source concentration in the system and electrode resistance. It is difficult to obtain uniform characteristics, and the efficiency and stability of electron emission are not sufficient.

JP 7-235255 A E. I. Elinson, Radiion Eng. Electron Phys. , 10 (1965) IDW96, Tech. Digest, p523 (1966)

  An object of the present invention is to provide a surface conduction electron-emitting device having high efficiency, high reliability, easy production and control of its characteristics, and uniform electron-emitting characteristics, and said electron-emitting device It is an object of the present invention to provide a uniform image forming apparatus with high efficiency, high reliability, high brightness, easy control of production and characteristics, and high image uniformity.

A first aspect of the present invention includes a substrate, a low potential electrode formed on the substrate, and a high potential electrode formed of a metal or semiconductor film and formed on the substrate. by applying a voltage between the electrodes, wherein an electron-emitting device for electron emission towards the high-potential electrode from the low potential electrode to form carbon nanotubes on the low-potential electrode, and between the electrodes The present invention relates to an electron-emitting device characterized in that the carbon nanotubes are grown in a direction of an electric field generated between the low potential electrode and the high potential electrode .
A second aspect of the present invention relates to an electron source characterized in that a plurality of electron-emitting devices according to claim 1 are arranged.
According to a third aspect of the present invention, there is provided an image forming apparatus characterized in that an image forming member for forming an image by collision of emitted electrons is provided at a position facing the electron source.
A fourth aspect of the present invention relates to a television provided with the image forming apparatus according to claim 3.

  As described above, by forming at least a part of the electron emission portion with carbonaceous material containing carbon nanotubes, the electrode distance of the electron emission portion is substantially narrower than when there is no carbon nanotube. Since the distance can be formed and controlled with high accuracy and ease, an electron-emitting device capable of operating at a low voltage and obtaining uniform electron emission characteristics can be provided. Furthermore, even in the conventional methods such as photolithography in which the distance between the electrodes could not be shortened, the short distance between the electrodes can be formed and controlled with high accuracy and simply as described above, so that it can be operated at a low voltage. In addition, uniform electron emission characteristics can be obtained.

In the electron-emitting device of the present invention, the carbonaceous material containing carbon nanotubes is preferably fixed to the electrode surface, more preferably the carbonaceous material containing carbon nanotubes is only one electrode, and even more preferably low The electron-emitting device is formed only on the potential electrode.
As described above, by fixing the carbonaceous material containing carbon nanotubes to the electrode surface, the carbonaceous material mainly composed of thin carbon nanotubes with a low work function is formed in the electron emission portion, so that it is highly efficient and remains. An electron-emitting device that is less susceptible to characteristic changes due to gas or the like can be obtained. Moreover, in the electron-emitting device of the present invention, when the carbonaceous material mainly composed of carbon nanotubes is formed only on one electrode, uniform electron emission characteristics can be obtained.

  Further, in the electron-emitting device of the present invention, the structure in which the carbon nanotube structure is arranged in the electron conduction direction can achieve higher electron emission efficiency, and the short inter-electrode distance can be further improved with high accuracy. In addition, since it can be formed and controlled easily, it can be operated at a low voltage and uniform electron emission characteristics can be obtained. In addition, by adopting the configuration as described above, even in a method such as photolithography, a shorter distance between electrodes can be formed and controlled with high accuracy and easily, so that it can operate at a low voltage and has uniform electron emission characteristics. Can be obtained.

Furthermore, in the electron-emitting device of the present invention, it is more preferable that the carbonaceous material containing carbon nanotubes is formed by concentrating on the opposite electrode end portions.
As described above, by forming the carbonaceous material containing carbon nanotubes in a concentrated manner at the opposite electrode end portions, the electric field is concentrated at the carbon nanotube tips, so that high electron emission efficiency can be obtained. In addition, since a short inter-electrode distance can be formed and controlled with higher accuracy and ease, it can be operated at a low voltage, and uniform electron emission characteristics can be obtained. Also in methods such as photolithography, by adopting the configuration as described above, a shorter distance between electrodes can be formed and controlled with high accuracy and convenience, so that it can operate at a low voltage and has uniform electron emission characteristics. Can be obtained.

As a method of forming at least a part of the electron emission part from carbonaceous material containing carbon nanotubes, there is a catalyst for depositing and growing carbon nanotubes from the gas phase on the electron emission part, for example, at least a part of the electrode or the electrode surface. And a method of selectively depositing and growing carbon nanotubes from the gas phase on the catalyst.
In this method, an uneven structure having a catalyst for depositing and growing carbon nanotubes from the gas phase at the bottom or top is provided on the surface of the electron emission portion, and carbon nanotubes are selectively deposited from the gas phase on the catalyst. It is preferable to grow.
According to the above-described method, an industrial method capable of forming an electron-emitting device having excellent characteristics with good reproducibility can be provided. Moreover, it was possible to easily solve the uniformity of the emission characteristics, which is the most important problem of the surface conduction type.

  As another method of forming at least a part of the electron emission portion with carbonaceous material containing carbon nanotubes, a manufacturing method in which carbon nanotubes are deposited using an electrochemical method or an electrode or a part of the electrode or the surface of the electrode, There is a method in which a carbonaceous material containing carbon nanotubes is deposited on a part of the electrode or on the surface of the electrode using an oxidation-reduction reaction on the electrode. Depending on these production methods, the emission element of the present invention can be provided by a simple method.

In addition, according to the present invention, there is provided an image forming apparatus including an electron-emitting device in which a carbonaceous material containing carbon nanotubes is formed in at least a part of an electron-emitting portion.
Since the image forming apparatus has the above-described uniform and high emission characteristics and includes a highly reliable electron-emitting device, the image forming apparatus has high emission efficiency, operates at a low voltage, and provides a highly reliable image forming apparatus. be able to. In addition, since the electron-emitting device is not easily affected by residual gas or the like, stable light emission can be obtained without using an ultra-high vacuum, and manufacturing is easy.

  As described above, the feature of the present invention is that the carbon nanotubes are arranged in the electron emission portion of the surface conduction electron-emitting device. Carbon nanotubes have a small work function (4.6 eV), and can emit electrons with a lower threshold voltage than when a metal electrode is used as an emitter. Furthermore, carbon nanotubes have less change in work function due to adsorption and deposition of these components even when there are residual components such as gas compared to metal electrodes, and the electron emission characteristics are less likely to change even at relatively low vacuum, There is an advantage that the characteristics hardly change even after long-term use. In addition, the carbon nanotube can be formed to a thickness of about 10 nm and a length of about several μm. Since the carbon nanotube has such a high aspect ratio and is a good conductor, the electric field is applied when an electric field is applied. Is particularly concentrated at the tip of the carbon nanotube in the vicinity of the high-resistance portion, and can efficiently emit electrons at a low voltage. The effect resulting from such a shape factor is a significant feature that cannot be expressed by conventional graphite or amorphous carbon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the configuration of the present invention will be illustrated and described.
FIG. 11 is a top view of an example of the electron-emitting device of the present invention. Although the basic configuration is similar to that of FIG. 9, the configuration in the vicinity of the high resistance portion 31 that is an electron emission portion is different.
FIG. 1 is a cross-sectional view of the vicinity of an electron emission portion of an example of the electron emission device of the present invention.
In FIG. 1, a pair of electrodes 21 and 22 are formed on a support (substrate) 1, and a high resistance portion 31 is formed between the electrodes. Carbon nanotubes 41 and 41 ′ are arranged on the electrodes 21 and 22 to form an electron emission portion. When a voltage is applied between the electrodes 21 with the electrode 21 as a low potential electrode and the electrode 22 as a high potential electrode, electrons are emitted from 21 to 22. Some of the emitted electrons, scattered electrons at the electrode 22, or secondary electrons are arranged in the upper part of the figure (not shown), and are attracted to the anode in a high potential state, so that the electrons are attracted to the anode. Is released towards.

  In the present invention, carbon nanotubes are arranged in the electron emission portion. Carbon nanotubes can be made to a thickness of about 10 nm and have a length of about several μm, and since they have such a high aspect ratio and are good conductors, when an electric field is applied as in the present invention, The electric field is particularly concentrated at the tip of the carbon nanotube in the vicinity of the high resistance portion, and the electron emission can be efficiently performed at a low voltage. Further, the carbon nanotube has a small work function (4.6 eV), and can emit electrons with a lower threshold voltage than when a metal electrode is used as an emitter. Furthermore, carbon nanotubes have less change in work function due to adsorption and deposition of these components even when there are residual components such as gas compared to metal electrodes, and the electron emission characteristics are less likely to change even at relatively low vacuum, There is an advantage that the characteristics hardly change even after long-term use.

As the electrodes 21 and 22, metals such as Mo, Ta, W, Cr, Ni, Pt, Ti, Al, Au, Cu, and Pd, or alloys, and metals such as Pd, Ag, Au, RuO ₂ , and Pd—Ag Alternatively, a metal oxide fine particle conductor, a semiconductor such as silicon, indium oxide, or tin oxide can be used. For forming the high resistance portion, a conventionally known forming method or electrode pattern formation using photolithography can be employed. The width L of the high resistance portion (between the electrodes) is preferably several hundred angstroms to several μm. Further, although the high resistance portion is illustrated as the groove shape L in this drawing, the conductive member may remain in a striped shape or the like. When the groove shape L is small, the current from the emitter electrode 21 to the gate electrode, called the gate current, increases, the electron emission efficiency decreases, and the current consumption increases. Further, when the width L of the high resistance portion (between the electrodes) is too large, the threshold voltage rises and the drive voltage rises.

  In order to form the carbon nanotubes 41 and 41 'on the electrode, a carbon nanotube separately synthesized by arc discharge or the like is attached or fixed electrochemically or physically, and after applying or printing in the same manner, a predetermined pattern is formed. Examples thereof include a patterning method and a method of depositing and growing on the electrode from the gas phase. As an electrochemical method, a method of depositing carbon nanotubes on an electrode by electrophoresis is known. Further, a deposition method using an oxidation-reduction reaction on the electrode, for example, a micellar electrolysis method using a ferrocene derivative or the like as a surfactant can also be preferably used.

  As a vapor deposition method, a CVD (chemical vapor deposition) method can be exemplified as a suitable example. This uses organic substances such as acetylene, ethylene, benzene, propylene, 2-amino-4,6-dichloro-s-triazine as a carbon source, decomposes them in the gas phase, and grows carbon nanotubes on the substrate. is there. In this case, the carbon nanotubes can be selectively grown on the catalyst by previously forming the catalyst on the substrate. For this reason, if the catalyst material is used as the electrode material, the carbon nanotubes are selectively formed on the electrode. It is preferable because it can be formed. Moreover, when a catalyst is formed in a specific place, carbon nanotubes can be selectively formed in a desired place.

  Examples of the catalyst material include Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Ge, Se, Zr, Nb, Mo, Ru, Rh, Pd, Ta, Pt, and Au. Mn, Fe, Co, Ni, Mo, and Pt are preferable. In FIG. 1, 51 and 52 correspond to a catalyst layer. As described above, the catalyst may be formed on the electrode as shown in the figure, or the electrode itself may be formed of a catalyst material. Further, it may be formed in a pattern or island shape instead of a uniform film as shown in FIG. Further, when the electrode is formed of fine particles, it may be present in the fine particles.

  FIG. 2 shows another configuration example of the electron-emitting device of the present invention. In this case, the carbon nanotube is formed on the electrode on the low potential side, and the high potential electrode side is composed of a film of metal or semiconductor. In this case, since the gate electrode is composed of a surface, more uniform emission characteristics can be obtained. In order to realize such a configuration, carbon nanotubes are formed by printing only on one electrode or are applied electrochemically by selectively applying a voltage to the electrode 21, as indicated by 41 in the figure. A method in which a catalyst is formed on only one electrode and vapor-phase grown, a method in which the electrode 21 is formed of a catalyst and an electrode 22 is formed by a non-catalytic conductive material and is formed by a vapor-phase growth method, a carbon nanotube formed in advance A method of patterning the film by a method such as photolithography can be exemplified.

FIG. 3 shows another configuration example of the electron-emitting device of the present invention. By disposing the carbon nanotube 41 between the electrodes, the substantial discharge distance between the electrodes 21 and 22 is changed from L to L _1. It is narrowed by. The discharge distance is an important factor in determining the emission threshold voltage and must be strictly controlled. When this interval changes depending on the element, the emission characteristics change. For example, when used as an electron emission source of a field emission display, uneven luminance is caused, which is not preferable. When a metal or semiconductor electrode is used for the electrodes 21 and 22, and the forming process is performed, the width L of the high resistance portion is relatively large on the order of μm, and the emission voltage becomes high if this is left as it is. In this configuration, by applying the method illustrated in FIG. 3, by controlling the growth of CNTs, a smaller L ₁ can be obtained, and a reduction in voltage can be achieved. Further, when the electrodes 21 and 22 are patterned by a known method such as photolithography, it is difficult to accurately control L at 0.5 μm or less due to the limit of photolithography. In this case, when the present invention is applied, a short L ₁ can be obtained with good reproducibility by controlling the growth of the carbon nanotubes, even if the L is, for example, about 1 μm, and the electron emission at a low voltage is stabilized. Can be realized. Thus, since it is possible to strictly control the length of the carbon nanotubes, it is possible to control the inter-electrode distance L ₁ a significant impact on release characteristics more precisely, yet a simple way. In addition, since the electron emission source is a carbon nanotube with a thin tip, high emission efficiency can be obtained as compared with a conventional planar emission electrode due to electric field concentration. Control of the length of the carbon nanotube can be realized by selecting the energizing time or voltage or the length of the carbon nanotube as a raw material in the electrochemical deposition method. Vapor phase growth is performed by controlling basic growth conditions such as the supply amount of raw material hydrocarbons, decomposition temperature, and growth time.

FIG. 4 shows a configuration example of another electron-emitting device according to the present invention, and shows a structure in which carbonaceous materials mainly composed of carbon nanotubes are arranged in the electron conduction direction in at least a part of the electron-emitting portion. It is a thing. In the figure, the carbon nanotubes 41 are arranged in the direction from the electrode 21 to the electrode 22, that is, the direction of electron conduction in the electron emission portion 31. With this configuration, together with the inter-electrode distance L ₁ can be more precisely controlled, because the carbon nanotubes in the direction of the electric field is arranged, it is possible to electron emission from the carbon nanotube tip causes more efficiently. Furthermore, since it is possible to strictly control the length of the carbon nanotubes, it is possible to control the inter-electrode distance L ₁ a significant impact on release characteristics more precisely, yet a simple way. In order to realize such a structure, as schematically shown in FIG. 5, a fine concave structure or a convex structure is provided on the electrode or the electrode, and the catalyst 51 is arranged corresponding to the concave and convex parts. A preferred example is a method of forming carbon nanotubes by vapor deposition. In FIG. 5, the electrode 22 is omitted.

  As the concavo-convex structure, a method of forming a concavo-convex pattern of a resist pattern by photolithography using a photoresist or the like, or a method of forming concavo-convex on the surface of a metal or the like by a method such as photolithography, porous film silica or porous alumina film A method of forming the hole and utilizing this hole can be preferably exemplified. In particular, porous alumina can be formed by anodic oxidation of aluminum, and a fine porous structure suitable for the growth of carbon nanotubes can be obtained. Therefore, it is the most preferable method in terms of industrial and orientation control. As a hole diameter or the diameter of a processus | protrusion, 5 nm-1 micrometer are preferable, More preferably, it is the range of 10 nm-500 nm.

  FIG. 7 shows another embodiment of the electron-emitting device of the present invention, which is an example in which carbon nanotubes are provided only on the cross section of the electrode 21 in FIG. In this case, since the electric field is further concentrated on the carbon nanotubes between the electrodes, higher efficiency electron emission can be obtained.

FIG. 6 shows another embodiment of the electron-emitting device of the present invention, which is an example in which carbon nanotubes are arranged in the electron conduction direction in FIG. In this case, since the electric field is further concentrated on the carbon nanotubes between the electrodes, higher efficiency of electron emission can be obtained, and L ₁ can be easily and accurately controlled.

In the present invention, the shape of the electrode is determined by many factors such as the wiring design of the emitter electrode and the gate electrode, the resistance of the electrode, the electron emission characteristics, and the application. Typically, W ₂ is 1 μm to 100 μm, and the sizes of W ₄ , 21 and 22 are in the range of 1 μm to 1 mm. The thickness of the electrodes 21 and 22 is in the range of 10 nm to several tens of μm.
As the carbon nanotubes that can be used, single-wall nanotubes and multi-wall nanotubes can be used. The diameter of the nanotube is 1 nm to 3 nm in the case of a single layer, and preferably 10 nm to 100 nm in the case of a multilayer. Further, single-walled nanotubes may gather together to form an aggregate on a bundle called a rope. Of these, multi-walled carbon nanotubes are particularly preferably used from the viewpoint of electron emission characteristics. These structures can be controlled by growth conditions, catalysts, and growth methods when forming the carbon nanotubes. The carbonaceous material containing carbon nanotubes may contain carbon polyhedral fine particles called nanoparticles. This is included as a by-product in the production of carbon nanotubes. The proportion of carbon nanotubes to make carbonaceous is preferably 20% or more, and more preferably 40% or more. When this ratio is low, the electron emission efficiency decreases. Further, the cap portion at the tip of the carbon nanotube can be removed. In this case, a more efficient release characteristic can be obtained by the shape effect, which is preferable. The cap can be removed by partially decomposing the carbon nanotubes by a method such as oxidation.
Although the carbon nanotubes have been described as ideally formed on the electrodes in the above drawings, they may also be formed on the high resistance portion outside the electrodes. However, since the electrodes 21 and 22 are short-circuited when this density is high, it is necessary to suppress the density to at least not short-circuit. Further, it is clear that the carbonaceous material made of carbon nanotubes may be formed on the electrode 22 unless otherwise specified. Further, the high resistance portion has been described as having an electrode that is completely missing in the shape of a groove, but an electrode member or the like may be formed intermittently, or a high resistance member may be present.

  The electron-emitting device of the present invention is applicable to many devices that require electron emission. In particular, it is particularly suitably used for an image forming apparatus generally called a field emission display or a vacuum micro display, taking advantage of the features of low voltage, high efficiency and uniformity.

FIG. 8 is a configuration example of a vacuum micro display using the electron-emitting device having the configuration example of FIG. In addition, the thing of the structure of this figure is an example of the image forming apparatus of this invention, and is not limited to the thing of the structure of this figure.
In the figure, 1 to 51 have the same meaning as in the previous figures. Reference numeral 71 denotes an insulating film, and 81 denotes an emitter wiring electrode. The gate wiring is made in a direction perpendicular to the paper surface and forms a matrix structure with the gate electrode. Reference numeral 91 denotes an anode electrode, and a potential such that emitter <gate <anode is applied to the selected pixel. Electrons extracted from the emitter by the gate voltage are accelerated according to the potential gradient and collide with the anode. Reference numeral 101 denotes a phosphor, and electrons penetrating the anode collide with the phosphor to promote the emission of the phosphor. Reference numeral 12 denotes a counter substrate, and a translucent member such as glass is used. The space between the substrates is sealed by an outer peripheral seal 111 such as frit glass, and a vacuum of 10 ⁻⁵ Torr to 10 ⁻⁸ Torr is maintained inside. The thickness d of the air gap is in the range of several tens of μm to several mm. As described above, the vacuum micro display according to the present invention has high efficiency and uniform electron emission characteristics and is equipped with a highly reliable electron emission element. A reliable image forming apparatus can be provided. In addition, since the electron-emitting device is not easily affected by residual gas or the like, stable light emission can be obtained at a degree of vacuum of about 10 ⁻⁶ Torr even if a high vacuum is not applied, and manufacturing is easy.

1. In a surface conduction electron-emitting device having a pair of electrodes and an electron emission portion formed between the electrodes, the electron emission portion is made of carbonaceous material mainly composed of thin carbon nanotubes with a low work function, and is highly efficient. In addition, an electron-emitting device that is not easily changed in characteristics by residual gas or the like has been provided.
2. The electron-emitting device according to the present invention in which the carbonaceous material mainly composed of carbon nanotubes is formed only on one electrode can obtain uniform electron emission characteristics in addition to the effect of 1.
3. In addition to the above effects, higher electron emission efficiency can be obtained. In addition, since a short inter-electrode distance can be formed and controlled with higher accuracy and ease, it can be operated at a low voltage, and uniform electron emission characteristics can be obtained. Also in a method such as photolithography, the present invention can form and control a further short inter-electrode distance with high accuracy and simplicity, so that it can be operated at a low voltage and uniform electron emission characteristics can be obtained.
4). Since the electric field is concentrated on the tip of the carbon nanotube, high electron emission efficiency can be obtained. In addition, since a short inter-electrode distance can be formed and controlled with higher accuracy and ease, it can be operated at a low voltage, and uniform electron emission characteristics can be obtained. Also, in a method such as photolithography, by adopting the structure of the present claim, a shorter distance between electrodes can be formed and controlled with high accuracy and convenience, so that it can operate at a low voltage and has uniform electron emission characteristics. Can be obtained.

5). An industrial method capable of forming the electron-emitting device having the above-described excellent characteristics with good reproducibility could be provided. In addition, according to this method, it was possible to easily solve the uniform emission characteristics, which is the most important problem of the surface conduction type.
6). The emission element of the present invention can be provided by a simple method.
7). Since the electron-emitting device having uniform and high emission characteristics and high reliability is provided, it is possible to provide a highly reliable image forming apparatus that has high luminous efficiency and operates at a low voltage. In addition, since the electron-emitting device is not easily affected by residual gas or the like, stable light emission can be obtained without using an ultra-high vacuum, and manufacturing is easy.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these Examples.
In the examples, the electrodes were W ₂ = 100 μm, W ₄ = 50 μm, and glass was used for the substrate.

Example 1
An undercoat layer made of SiO ₂ was formed on a glass substrate with a thickness of 500 A, and the electrode structure shown in FIG. 1 was formed using a photolithography method. L = 2 μm.
Subsequently, carbon nanotubes were generated at a decomposition temperature of 650 ° C. using acetylene as a carbon source and ammonia as a diluent gas. The carbon nanotube was formed so as to substantially cover the Ni surface, and the electron-emitting device shown in FIG. 1 could be formed.
When the characteristics of the device were measured in an anode voltage of 1 KV in a vacuum of 10 ⁻⁷ Torr, stable electron emission was confirmed, and the emission efficiency (emission current / gate current) was 2%. Also, the discharge characteristics hardly changed even during continuous discharge.

Comparative Example 1
In Example 1, the emission characteristics were measured without forming carbon nanotubes. As a result, the emission efficiency was about 1%, and the threshold voltage was twice that of the Example. Moreover, it was confirmed that the discharge characteristics gradually deteriorated with continuous energization.

Example 2
In Example 1, carbon nanotubes were formed only on the electrode 21 (low potential electrode). When the electron emission characteristics of this device were measured in the same manner, the efficiency and threshold voltage were almost the same as in Example 1, but the emission characteristics were more stable. Further, as in Example 1, no change in the release characteristics with time was observed.

Example 3
After forming a subbing layer made of SiO ₂ on glass to a thickness of 500 A, a Ni film was formed to a thickness of 50 nm by sputtering. The electrode structure shown in FIG. 1 was formed using a photolithography method. L = 2 μm. Furthermore, carbon nanotubes were generated at a decomposition temperature of 650 ° C. using acetylene as a carbon source and ammonia as a diluent gas. The carbon nanotube was formed so as to cover the Ni surface and the cross section, and the electron-emitting device shown in FIG. 3 could be formed. The carbon nanotubes grew even in the direction from the electrode 21 to the electrode 22, and the actual interelectrode distance could be controlled to 100 nm. When the characteristics of the device were measured in a vacuum of 10 ⁻⁷ Torr at an anode voltage of 1 KV, stable electron emission was confirmed, and the emission efficiency (emission current / gate current) was 0.5%. Also, the discharge characteristics hardly changed even during continuous discharge.

Comparative Example 2
In Example 3, an undercoat layer made of SiO ₂ was formed on a glass with a thickness of 500 A, and then a Ni film was formed with a thickness of 50 nm by a sputtering method. An attempt was made to form an electrode structure with L = 100 nm using a photolithographic method, but there was no pattern reproducibility, and the reproducibility of the emission characteristics measured without providing carbon nanotubes was not obtained. On the other hand, in Example 3, as described above, L = 2 μm, but by providing CNT, the width of the emission part was substantially made 100 nm, and stable emission was obtained.

Example 4
An ultrafine Pd film was formed as an electrode, and a 100 nm crack was formed by forming treatment. Subsequently, carbon nanotubes were generated at a decomposition temperature of 650 ° C. using acetylene as a carbon source and ammonia as a diluent gas. The carbon nanotube was formed so as to cover the Pd surface and the cross section, and the electron-emitting device shown in FIG. 3 could be formed. The carbon nanotubes grew even in the direction from the electrode 21 to the electrode 22, and the actual interelectrode distance could be controlled to 10 nm. When the characteristics of the device were measured in a vacuum of 10 ⁻⁷ Torr at an anode voltage of 1 KV, stable electron emission was confirmed, and the emission efficiency (emission current / gate current) was 0.3%. Also, the discharge characteristics hardly changed even during continuous discharge.

Comparative Example 3
An ultrafine Pd film was formed as an electrode, and a 10 nm crack was formed by a forming process. When the characteristics of this device were measured in a vacuum of 10 ⁻⁷ Torr at an anode voltage of 1 KV, electron emission was confirmed, but the stability was poor, and the emission efficiency (emission current / gate current) was 0.1%. It was. In addition, a decrease in emission efficiency was observed in the continuous discharge.

Comparative Example 4
In Example 4, amorphous carbon was deposited on the electrode 21 by energizing the electrode 21 without forming carbon nanotubes. The efficiency of this element was 0.2%, and Example 4 was superior. Moreover, Example 4 was excellent also in reproducibility.

Example 5
After forming a subbing layer made of SiO ₂ on glass to a thickness of 500 A, a Ni film was formed to a thickness of 50 nm by sputtering. On top of that, Al was further formed to a thickness of 50 nm. Subsequently, Al was made porous alumina by an anodic oxidation method. At this time, the reactive ion etching process was performed so that the holes formed in the alumina reached Ni. In this way, the electrode structure shown in FIG. 5 was formed. L was 2 μm. The alumina pores were about 40 nm in diameter. Furthermore, carbon nanotubes were generated at a decomposition temperature of 650 ° C. using acetylene as a carbon source and ammonia as a diluent gas. The carbon nanotubes were formed vertically in the alumina pores, and the electron-emitting device shown in FIG. 5 could be formed. The carbon nanotubes grew in parallel with the substrate even in the direction from the electrode 21 to the electrode 22, and the actual distance between the electrodes could be controlled to 100 nm. When the characteristics of this device were measured in a vacuum of 10 ⁻⁷ Torr at an anode voltage of 1 KV, stable electron emission was confirmed, and the emission efficiency (emission current / gate current) was 0.6%. Further, the emission characteristics did not change even during continuous discharge.

Example 6
In Example 5, porous alumina was formed only at the end of the electrode 21. In this way, the electrode structure shown in FIG. 6 was formed (however, FIG. 6 does not show the electrode 22 on the right side). L was 2 μm. The alumina pores were about 40 nm in diameter. Furthermore, carbon nanotubes were generated at a decomposition temperature of 650 ° C. using acetylene as a carbon source and ammonia as a diluent gas. The carbon nanotubes were formed vertically in the alumina pores, and the electron-emitting device shown in FIG. 6 could be formed. The carbon nanotubes grew in parallel with the substrate from the electrode 21 to the electrode 22, and the actual interelectrode distance could be controlled to 100 nm.
When the characteristics of this device were measured in a vacuum of 10 ⁻⁷ Torr at an anode voltage of 1 KV, stable electron emission was confirmed, and the emission efficiency (emission current / gate current) was 0.6%. Further, the emission characteristics did not change even during continuous discharge.

Example 7
After forming an undercoat layer made of SiO ₂ on glass to a thickness of 500 A, a SnO ₂ / In ₂ O ₃ film was formed to a thickness of 50 nm by sputtering. The electrode structure shown in FIG. 1 was formed using a photolithography method. L = 1 μm.
By separately using carbon nanotubes (length 0.8 μm, diameter 10 nm) prepared by arc discharge method using ferrocene derivative surfactant FPEG (manufactured by Dojin Kagaku), FPEG 5-fold support salt (LiBr) is used together Carbon nanotubes were made into micelles. A constant potential electric field of 0.5 V was applied using the electrode 21 as an anode and platinum as a cathode, and carbon nanotubes were deposited on the electrode. The carbon nanotubes were formed so as to cover the SiO ₂ surface and the cross section, and the electron-emitting device shown in FIG. 3 could be formed. Carbon nanotubes also grew in the direction from the electrode 21 to the electrode 22, whereby the actual interelectrode distance could be controlled to 200 nm. When the characteristics of the device were measured in a vacuum of 10 ⁻⁷ Torr at an anode voltage of 1 KV, stable electron emission was confirmed, and the emission efficiency (emission current / gate current) was 0.4%. Also, the discharge characteristics hardly changed even during continuous discharge.

Example 8
The electron-emitting devices of Example 3 were formed in a 16 × 16 array to form a vacuum microdisplay shown in FIG. SiO ₂ was used for the insulating film 71 and Al was used for the emitter wiring electrode 81. Al was used for the anode electrode 91. ZnO: Zn was used for the phosphor. The distance between the emitter and the anode was 2 mm. The degree of vacuum was 10 ⁻⁷ Torr. This display produced extremely uniform light emission, and no decrease in brightness was observed even during continuous operation.

It is sectional drawing of the electron emission part vicinity of one structural example (The carbon nanotubes 41 and 41 'are arrange | positioned on an electrode and an electron emission part is formed) of the electron emission element of this invention. It is sectional drawing of the electron emission part vicinity of another structural example (CNT is formed in the electrode of the low electric potential side, and the high electric potential electrode side is comprised with films | membranes, such as a metal or a semiconductor) of the electron emission element of this invention. It is sectional drawing of the electron emission part vicinity of another structural example (CNT is arrange | positioned between electrodes) of the electron emission element of this invention. It is sectional drawing of the electron emission part vicinity of another structural example (The structure in which the carbonaceous material which has CNT as a main component was arranged in the electron conduction direction) of the electron emission element of this invention. It is sectional drawing of the electron emission part vicinity of another structural example (structure which provided the fine concave structure or convex structure on the electrode) of the electron-emitting element of this invention. It is sectional drawing of the electron emission part vicinity of another structural example (structure which arranged CNT in the electron conduction direction in FIG. 7) of the electron-emitting element of this invention. FIG. 6 is a cross-sectional view of the vicinity of an electron emission portion of another configuration example of the electron emission element of the present invention (configuration in which CNTs are provided only on the cross section of the electrode 21 in FIG. 5). FIG. 4 is a cross-sectional view of a vacuum micro display using the electron-emitting device having the configuration example of FIG. 3. It is the top view which showed the conventional surface conduction type element structure. It is sectional drawing which showed the conventional surface conduction type element structure. It is a top view of an example of the electron-emitting device of the present invention. FIG. 2 is an enlarged explanatory view of an electron emission portion in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 12 Counter substrate 21 Electrode 22 Electrode 31 High resistance part formed between electrodes 32 Groove formed between electrodes or altered high resistance part 41 Carbon nanotube 41 ′ Carbon nanotube 51 Catalyst layer 52 Catalyst layer 61 Fine concave Structure 71 Insulating film 81 Emitter wiring electrode 91 Anode electrode 101 Phosphor 111 Peripheral seal d Gap thickness L Width of high resistance portion (between electrodes) or groove formed between electrodes L ₁ High resistance portion (between electrodes) Width or groove formed between electrodes W ₁ Total length of cathode electrode and gate electrode (1 μm to 1 mm)
The width (1 μm to 100 μm) of the high resistance portion for forming the W ₂ electron emission portion by the forming process. However, W ₂ <W ₁
W ₃ cathode electrode and gate electrode width (1 μm to 1 mm)
Length of the high resistance portion (1 μm to 1 mm) for forming the W ₄ electron emitting portion by forming process. However, W ₄ <W ₃

Claims (4)

A substrate, a low-potential electrode formed on the substrate, and a high-potential electrode formed of a metal or semiconductor film and formed on the substrate, and applying a voltage between the electrodes. it is, the electron emitter to emit electrons toward the high-potential electrode from the low potential electrode, wherein the forming the carbon nanotube on the low potential electrode, and wherein the carbon nanotube between the two electrodes An electron-emitting device grown in a direction of an electric field generated from a low potential electrode toward the high potential electrode .   An electron source comprising a plurality of electron-emitting devices according to claim 1 arranged.   An image forming apparatus comprising an image forming member for forming an image by collision of emitted electrons at a position facing the electron source according to claim 2.   A television comprising the image forming apparatus according to claim 3.

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